CondaPkg.jl

Add Conda dependencies to your Julia project.

Overview

This package is a lot like Pkg from the Julia standard library, except that it is for managing Conda packages.

• Conda dependencies are defined in CondaPkg.toml, which is analogous to Project.toml.
• CondaPkg will install these dependencies into a Conda environment specific to the current Julia project. Hence dependencies are isolated from other projects or environments.
• Functions like add, rm, status exist to edit the dependencies programatically.
• Or you can do pkg> conda add some_package to edit the dependencies from the Pkg REPL.

Install

pkg> add CondaPkg

Specifying dependencies

Pkg REPL

The simplest way to specify Conda dependencies is through the Pkg REPL, just like for Julia dependencies. For example:

julia> using CondaPkg
julia> # now press ] to enter the Pkg REPL
pkg> conda status                # see what we have installed
pkg> conda add python perl       # adds conda packages
pkg> conda pip_add build         # adds pip packages
pkg> conda rm perl               # removes conda packages
pkg> conda run python --version  # runs the given command in the conda environment

For more information do ? or ?conda from the Pkg REPL.

Note: We recommend against adding Pip packages unless necessary - if there is a corresponding Conda package then use that. Pip does not handle version conflicts gracefully, so it is possible to get incompatible versions.

Functions

These functions are intended to be used interactively when the Pkg REPL is not available (e.g. if you are in a notebook):

• status() shows the Conda dependencies of the current project.
• add(pkg; version="", channel="") adds/replaces a dependency.
• rm(pkg) removes a dependency.
• add_channel(channel) adds a channel.
• rm_channel(channel) removes a channel.
• add_pip(pkg; version="") adds/replaces a pip dependency.
• rm_pip(pkg) removes a pip dependency.

CondaPkg.toml

Finally, you may edit the CondaPkg.toml file directly. Here is a complete example:

channels = ["anaconda", "conda-forge"]

[deps]
# Conda package names and versions
python = ">=3.5,<4"
perl = ""

[deps.llvmlite]
# Long syntax to specify other fields, such as the channel
version = ">=0.38,<0.39"
channel = "numba"

[pip.deps]
# Pip package names and versions
build = "~=0.7.0"
six = ""
some-remote-package = "@ https://example.com/foo.zip"
some-local-package = "@ ./foo.zip"

Access the Conda environment

• envdir() returns the root directory of the Conda environment.
• withenv(f) returns f() evaluated in the Conda environment.
• which(progname) find the program in the Conda environment.
• resolve(; force=false) resolves dependencies. You don't normally need to call this because the other API functions will automatically resolve first. Pass force=true if you change a CondaPkg.toml file mid-session.
• gc() removes unused caches to save disk space.

Examples

Assuming one of the dependencies in CondaPkg.toml is python then the following runs Python to print its version.

# Simplest version.
CondaPkg.withenv() do
  run(`python --version`)
end
# Guaranteed not to use Python from outside the Conda environment.
CondaPkg.withenv() do
  python = CondaPkg.which("python")
  run(`$python --version`)
end
# Explicitly specifies the path to the executable (this is package-dependent).
CondaPkg.withenv() do
  python = joinpath(CondaPkg.envdir(), Sys.iswindows() ? "python.exe" : "bin/python")
  run(`$python --version`)
end

Details

Conda packages

These are identified by a name and version.

The version must be a Conda version specifier, or be blank.

Conda channels

If not specified in CondaPkg.toml, packages are installed from the conda-forge channel.

Pip packages

These are identified by a name and version.

The version must be a Pip version specifier, or be blank.

Direct references such as foo @ http://example.com/foo.zip are allowed. As a special case if the URL starts with . then it is interpreted as a path relative to the directory containing the CondaPkg.toml file.

Backends

This package has a number of different "backends" which control exactly which implementation of Conda is used to manage the Conda environments. You can explicitly select a backend by setting the environment variable JULIA_CONDAPKG_BACKEND to one of the following values:

• MicroMamba: Uses MicroMamba from the package MicroMamba.jl.
• System: Use a pre-installed Conda. If JULIA_CONDAPKG_EXE is set, that is used. Otherwise we look for conda, mamba or micromamba in your PATH.
• Null: Don't use CondaPkg to manage dependencies. Use this if you are in a pre-existing Conda environment that already satisfies the dependencies of your project. It is up to you to ensure any required packages are installed.

The default backend is an implementation detail, but is currently MicroMamba.

If you set JULIA_CONDAPKG_EXE but not JULIA_CONDAPKG_BACKEND then the System backend is used.

Verbosity

You can control the verbosity of any conda or pip commands executed by setting the environment variable JULIA_CONDAPKG_VERBOSITY to a number:

• -1 is quiet mode (the default).
• 0 is normal mode.
• 1, 2, etc. are verbose modes, useful for debugging.